class_docstr: Parse json-string of one line in annotation file to dict format.
  
  Args:
      keys (list[str]): Keys in both json-string and result dict. Defaults
          to ['filename', 'text'].
code: def __init__(
      self, keys: Tuple[str, str] = ["filename", "text"]
  ) -> None:
      assert isinstance(keys, list)
      assert len(keys) > 0
      self.keys = keys
  
file_path: mmocr/mmocr/utils/parsers.py
imports: import json
  import warnings
  from typing import Dict, Tuple
  from mmocr.registry import TASK_UTILS
  from mmocr.utils.string_utils import StringStripper
label_desc: Use image node_id 1 to create a new LineJsonParser object  with example: obj = LineJsonParser(keys)